I am the very proud owner of a Jaguar XJ8 4.0 LWB Sovereign. I used to have a Jaguar XJ6 $.0 before and I much prefer the XJ8. I used to use 10-40 oil in my Jaguar XJ6 is this still a good choice for my Jaguar XJ8 ?.

 

"That depends....."
If you live where it gets below freezing, 10W-40 is too thick. OEM spec is 5W-30. 10 is probably fine in Florida....
FWIW, I run 5W-30 Castrol High Mileage (synthetic blend) in mine without issue
-Steve-